This is a bug fix release of the Reactive Extensions for JavaScript (RxJS) for version 4.0 to fix a number of issues. The most prominent being the issue with fromPromise(promise) was swallowing errors from Observable instances which is now fixed. Looking forward, we will continue to work on performance as well as the modular design for those who want to pick and choose which pieces from NPM they want to use.

Performance Work

Work continued on performance with Rx.Observable.onErrorResumeNext, Rx.Observable.mergeDelayError as well as our join patterns. Expect this to continue throughout the lifecycle of v4.x.

Bugs Fixed:

These were the bugs fixed during this release since 4.0.0:

• #969 - fix for timeout without other Observable
• #964 - fixed shared state for zip, combineLatest and withLatestFrom in subscribeCore
• #963 - Angular broken with latest release
• #957 - fix issue with fromEvent not firing
• #955 - compilation issue fix